This heavy duty solenoid valve is suitable for Ammonia, R-12, R-22, and R-502, other refrigerants, certain oils and other fluids approved for use in refrigeration. The S4A is a pilot operated, semi-steel bodied valve. The valve may be opened by means of the manual opening stem for servicing or in case of electrical power failure. The Type S4A Solenoid Valve is furnished with FPT Internal NPT (U.S. Standard Taper Pipe Thread), Socket Weld, Weld Neck or ODS (solders over copper tubing of given diameter) connections. The valve may be easily removed from between the flanges for servicing. It is advisable to install a strainer upstream of each valve to prevent entrance of foreign material into the valve and the rest of the system. Refrigerating Specialties strainers are available to close-couple to valve inlets.